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Literature summary for 4.2.1.20 extracted from

  • Ferrari, D.; Niks, D.; Yang, L.H.; Miles, E.W.; Dunn, M.F.
    Allosteric communication in the tryptophan synthase bienzyme complex: roles of the beta-subunit aspartate 305-arginine 141 salt bridge (2003), Biochemistry, 42, 7807-7818.
    View publication on PubMed

Activating Compound

Activating Compound Comment Organism Structure
Cs+ wild-type enzyme alpha-site is activated by the formation of the alpha-aminoacrylate Schiff base at the beta-site Salmonella enterica subsp. enterica serovar Typhimurium
Na+ wild-type enzyme alpha-site is activated by the formation of the alpha-aminoacrylate Schiff base at the beta-site Salmonella enterica subsp. enterica serovar Typhimurium
NH4+ wild-type enzyme alpha-site is activated by the formation of the alpha-aminoacrylate Schiff base at the beta-site Salmonella enterica subsp. enterica serovar Typhimurium

Protein Variants

Protein Variants Comment Organism
D305A forms a bienzyme complex with impaired allosteric communication, altered beta-site substrate reaction specificity, the Na+ form of the alpha-site of the mutant is no longer activated by the formation of the alpha-aminoacrylate Schiff base at the beta-site, but this can be restored by replacing Na+ with NH4+ or Cs+ Salmonella enterica subsp. enterica serovar Typhimurium
R141A forms a bienzyme complex with impaired allosteric communication, impaired beta-site catalytic acitivity, the Na+ form of the alpha-site of the mutant is no longer activated by the formation of the alpha-aminoacrylate Schiff base at the beta-site, no restoration by NH4+ or Cs+ Salmonella enterica subsp. enterica serovar Typhimurium

Inhibitors

Inhibitors Comment Organism Structure
DL-alpha-glycerol 3-phosphate alone or in presence of Na+ and Cs+ for wild-type enzyme, for the mutants R141A and D305A the presence of Na+ and NH4+ reverses the inhibitory effect Salmonella enterica subsp. enterica serovar Typhimurium

KM Value [mM]

KM Value [mM] KM Value Maximum [mM] Substrate Comment Organism Structure
additional information
-
additional information dissociation constants, kinetics Salmonella enterica subsp. enterica serovar Typhimurium

Organism

Organism UniProt Comment Textmining
Salmonella enterica subsp. enterica serovar Typhimurium
-
-
-

Reaction

Reaction Comment Organism Reaction ID
L-serine + 1-C-(indol-3-yl)glycerol 3-phosphate = L-tryptophan + D-glyceraldehyde 3-phosphate + H2O also catalyses the conversion of serine and indole into tryptophan and water, and of indoleglycerol phosphate into indole and glyceraldehyde phosphate (the latter reaction was listed formerly as EC 4.2.1.8), salt bridge betaAsp305-betaArg141 plays a crucial role in both the formation of the closed conformation of the beta-site and the transmission of allosteric signals between the alpha- and beta-sites that switch the alpha-site on and off, mechanism Salmonella enterica subsp. enterica serovar Typhimurium

Substrates and Products (Substrate)

Substrates Comment Substrates Organism Products Comment (Products) Rev. Reac.
1-(indol-3-yl)glycerol 3-phosphate alpha-subunit of the bienzyme complex, alpha-reaction Salmonella enterica subsp. enterica serovar Typhimurium D-glyceraldehyde 3-phosphate + indole
-
?
L-serine + indole beta-subunit of the bienzyme complex, beta-reaction Salmonella enterica subsp. enterica serovar Typhimurium L-tryptophan + H2O
-
?
L-serine + indoline
-
Salmonella enterica subsp. enterica serovar Typhimurium dihydroiso-L-tryptophan + H2O i.e. DIT ?
additional information allosteric interactions that regulate substrate channeling and catalysis in the bienzyme complex are triggered by covalent ractions at the beta-site and binding of substrate/product to te alpha-site, transmission of the allosteric signals between the alpha- and beta-catalytic sites is modulated by an ensemble of weak bonding interactions consisting of salt bridges, hydrogen bonds, and van der Waals contacts that switch the subunits between open and closed conformations Salmonella enterica subsp. enterica serovar Typhimurium ?
-
?

Subunits

Subunits Comment Organism
More salt-bridges extending between the subunits involve alphaAsp56, betaLys167, beta-Asp305, and betaR141 Salmonella enterica subsp. enterica serovar Typhimurium
tetramer alpha2beta2 enzyme complex Salmonella enterica subsp. enterica serovar Typhimurium

Temperature Optimum [°C]

Temperature Optimum [°C] Temperature Optimum Maximum [°C] Comment Organism
25
-
assay at Salmonella enterica subsp. enterica serovar Typhimurium

Turnover Number [1/s]

Turnover Number Minimum [1/s] Turnover Number Maximum [1/s] Substrate Comment Organism Structure
additional information
-
additional information activities of wild-type and mutants in presence of different effectors Salmonella enterica subsp. enterica serovar Typhimurium
0.033
-
indole beta-reaction, mutant R141A, pH 7.8, 25°C Salmonella enterica subsp. enterica serovar Typhimurium
0.16
-
1-(indol-3-yl)glycerol 3-phosphate overall-reaction, mutant R141A, pH 7.8, 25°C Salmonella enterica subsp. enterica serovar Typhimurium
0.3
-
1-(indol-3-yl)glycerol 3-phosphate alpha-reaction, wild-type, and overall-reaction, wild-type and mutant D305A, pH 7.8, 25°C Salmonella enterica subsp. enterica serovar Typhimurium
0.36
-
1-(indol-3-yl)glycerol 3-phosphate alpha-reaction, mutant R141A, pH 7.8, 25°C Salmonella enterica subsp. enterica serovar Typhimurium
0.44
-
1-(indol-3-yl)glycerol 3-phosphate alpha-reaction, mutant D305A, pH 7.8, 25°C Salmonella enterica subsp. enterica serovar Typhimurium
0.88
-
indole beta-reaction, mutant D305A, pH 7.8, 25°C Salmonella enterica subsp. enterica serovar Typhimurium
1.6
-
indole beta-reaction, wild-type, pH 7.8, 25°C Salmonella enterica subsp. enterica serovar Typhimurium
6.08
-
indole beta-reaction, mutant D305A, pH 7.8, 25°C Salmonella enterica subsp. enterica serovar Typhimurium

pH Optimum

pH Optimum Minimum pH Optimum Maximum Comment Organism
7.8
-
assay at Salmonella enterica subsp. enterica serovar Typhimurium

Cofactor

Cofactor Comment Organism Structure
pyridoxal 5'-phosphate dependent on Salmonella enterica subsp. enterica serovar Typhimurium